The objective of this project is to conduct Phase I and Phase II clinical trials of candidate AIDS vaccines among HIV-seronegative volunteers at low risk of infection. The Offeror shall furnish all the necessary services, qualified personnel, materials, equipment, and facilities as needed to conduct collaborative trials sponsored by the National Institutes of Health and done at multiple institutions. The goal of these Phase I and Phase II studies is to define the safety, toxicity, and immunogenicity of such vaccines. The Offeror will cooperate as appropriate with other component parts of the AIDS Vaccine Evaluation Group (AIDS Vaccine Evaluation Units, Central Immunology laboratory, Data Coordinating and Analysis Center, and Central Repository). The Offeror will follow common protocols to test approved candidate vaccines and to determine the optimal dosage regimen. The Offeror will recruit, screen, and inoculate an average of 200 volunteers per year. The Offeror will conduct appropriate laboratory evaluations for toxicity (hematologic, hepatic/neural, gastrointestinal, neurologic, dermatologic), for viral antigens and antibodies (ELISA, Western Blot, Neutralization assays), and for changes in immunologic function (changes in T4/T8 cell counts, assays of cell mediated immunity, skin tests). The Offeror will be responsible for maintaining individual confidential patient records. The Offeror will record pertinent data obtained from the clinical trials, enter the data onto a microcomputer, and transmit this data via modem to the Data Coordinating and Analysis Center.